【摘要】：由于隧道工程特有的工程性質(zhì),導(dǎo)致隧道結(jié)構(gòu)的受力、變形和破壞往往形式復(fù)雜、變化多樣,且影響因素眾多。而這些影響因素來(lái)自于荷載、材料、結(jié)構(gòu)幾何形狀等諸多方面,且大多都為隨機(jī)變化量,包含眾多的不確定性。隨著工程技術(shù)、理論研究的發(fā)展,基于確定性研究所得的理論成果表現(xiàn)出一定的不合理性。專(zhuān)家學(xué)者對(duì)這些影響隧道結(jié)構(gòu)的隨機(jī)變量開(kāi)展了大量的基礎(chǔ)研究工作,形成以可靠度理論為基礎(chǔ)的概率極限設(shè)計(jì)方法。隨著我國(guó)隧道工程建設(shè)的大力發(fā)展,危害程度大、治理費(fèi)用高、施工風(fēng)險(xiǎn)大的軟弱圍巖大變形災(zāi)害已成為困擾地下工程界的一個(gè)重大問(wèn)題,而軟巖大變形隧道穩(wěn)定性的研究是工程科研人員亟需深入研究解決的一大課題。本文介紹了結(jié)構(gòu)可靠度以及軟弱圍巖大變形理論的國(guó)內(nèi)外研究現(xiàn)狀與發(fā)展,在相關(guān)文獻(xiàn)及研究成果的基礎(chǔ)上對(duì)結(jié)構(gòu)可靠度及軟巖大變形理論進(jìn)行整理總結(jié)。再以蘭渝線(xiàn)天池坪隧道為工程背景,利用有限元軟件ANSYS采用DP屈服準(zhǔn)則對(duì)天池坪隧道進(jìn)行二維數(shù)值模擬,對(duì)隧道臺(tái)階法連續(xù)開(kāi)挖施工過(guò)程進(jìn)行模擬,在考慮圍巖、支護(hù)結(jié)構(gòu)材料等影響隧道結(jié)構(gòu)隨機(jī)特性的參數(shù)外,嘗試將時(shí)間隨機(jī)場(chǎng)轉(zhuǎn)化為圍巖擾動(dòng)影響系數(shù),構(gòu)造包含時(shí)間隨機(jī)場(chǎng)的極限位移功能函數(shù)及極限狀態(tài)方程,利用蒙特卡洛法對(duì)隧道開(kāi)挖過(guò)程中隧道結(jié)構(gòu)的可靠度進(jìn)行計(jì)算,研究各臺(tái)階開(kāi)挖過(guò)程中隧道結(jié)構(gòu)的隨機(jī)特性。在各臺(tái)階開(kāi)挖過(guò)程中,圍巖彈性模量對(duì)隧道拱頂沉降的影響最大,隨著圍巖彈性模量的增大隧道拱頂沉降量(負(fù)數(shù))增大;支護(hù)結(jié)構(gòu)厚度和支護(hù)結(jié)構(gòu)彈性模量對(duì)拱頂沉降的影響次之,影響規(guī)律均為隨著支護(hù)厚度和支護(hù)彈模的增大隧道拱頂沉降量(負(fù)數(shù))增大;圍巖密度的隨機(jī)特性對(duì)拱頂沉降的影響較小,隨著圍巖密度的增大隧道拱頂沉降量(負(fù)數(shù))減小;以上規(guī)律在隧道開(kāi)挖過(guò)程中均保持不變;但隧道開(kāi)挖完成后,支護(hù)結(jié)構(gòu)厚度、支護(hù)結(jié)構(gòu)彈性模量對(duì)拱頂沉降的影響反而小于圍巖密度對(duì)拱頂沉降影響,這與隧道開(kāi)挖過(guò)程中的規(guī)律相反,即說(shuō)明支護(hù)結(jié)構(gòu)在隧道開(kāi)挖過(guò)程中對(duì)隧道穩(wěn)定性的影響要大于對(duì)隧道開(kāi)挖完成后的影響,也就驗(yàn)證了支護(hù)結(jié)構(gòu)隨機(jī)特性在隧道開(kāi)挖過(guò)程中對(duì)隧道的穩(wěn)定作用較大。所以在軟巖大變形隧道的開(kāi)挖過(guò)程中初期支護(hù)結(jié)構(gòu)的施做對(duì)隧道結(jié)構(gòu)及圍巖的穩(wěn)定性意義重大;但不論在隧道開(kāi)挖過(guò)程中還是隧道開(kāi)挖完成后,圍巖彈性模量對(duì)隧道拱頂沉降的影響均為最大,所以圍巖的不確定性仍是隧道開(kāi)挖過(guò)程中影響隧道結(jié)構(gòu)可靠的主要原因。
[Abstract]:Due to the special engineering properties of tunnel engineering, the stress, deformation and failure of tunnel structure are often complicated, varied and have many influencing factors. These factors come from loads, materials, structural geometry and many other aspects, and most of them are random variables, including a lot of uncertainties. With the development of engineering technology and theoretical research, the theoretical results based on deterministic research show some irrationality. Experts and scholars have carried out a lot of basic research on these random variables which affect the tunnel structure and formed a probability limit design method based on reliability theory. With the great development of tunnel engineering construction in China, the disaster of large deformation of soft surrounding rock, which is of great harm degree, high treatment cost and high construction risk, has become a major problem puzzling the underground engineering circle. The research on the stability of soft rock tunnel with large deformation is an urgent task for engineering researchers. This paper introduces the present situation and development of the theory of structural reliability and large deformation of soft rock at home and abroad, and summarizes the theory of structural reliability and large deformation of soft rock on the basis of relevant literature and research results. Then taking Tianchiping tunnel of Lanyu line as the engineering background, using the finite element software ANSYS to carry on the two-dimensional numerical simulation of Tianchiping tunnel by using DP yield criterion, and to simulate the construction process of the continuous excavation of the tunnel by step method, considering the surrounding rock. Besides the parameters which affect the random characteristics of tunnel structure, the time random field is transformed into the disturbance coefficient of surrounding rock, and the function of limit displacement and the limit state equation including time random field are constructed. The reliability of tunnel structure during tunnel excavation is calculated by Monte Carlo method, and the stochastic characteristics of tunnel structure during step excavation are studied. In the process of every step excavation, the elastic modulus of surrounding rock has the greatest influence on the settlement of the tunnel arch roof, and with the increase of the elastic modulus of the surrounding rock, the settlement amount of the tunnel arch roof (negative number) increases. The thickness of supporting structure and elastic modulus of supporting structure have the second influence on the settlement of arch roof, the law of influence is that with the increase of supporting thickness and elastic modulus of support, the settlement (negative number) of tunnel arch roof increases. The random characteristics of surrounding rock density have little influence on the settlement of arch roof. With the increase of surrounding rock density, the settlement (negative number) of tunnel arch roof decreases, and the above laws remain unchanged in the course of tunnel excavation, but the thickness of supporting structure after tunnel excavation is completed. The influence of elastic modulus of supporting structure on the settlement of arch roof is smaller than that of surrounding rock density on the settlement of arch roof, which is contrary to the law in the course of tunnel excavation. That is to say, the influence of supporting structure on tunnel stability in the course of tunnel excavation is greater than that on tunnel stability after tunnel excavation, and it is verified that the stochastic characteristics of supporting structure play a greater role in the stability of tunnel in the course of tunnel excavation. Therefore, it is of great significance for the stability of tunnel structure and surrounding rock to make the initial supporting structure in the excavation process of large deformation tunnel in soft rock, but no matter in the course of tunnel excavation or after the tunnel excavation is completed, the construction of supporting structure is of great significance to the stability of tunnel structure and surrounding rock. The influence of elastic modulus of surrounding rock on the settlement of tunnel arch is the biggest, so the uncertainty of surrounding rock is still the main reason that affects the reliability of tunnel structure in the course of tunnel excavation.
【學(xué)位授予單位】：蘭州交通大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類(lèi)號(hào)】：U451

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本文編號(hào)：2181911